Chair iron for tiltable seats and backs



Dec. 21, 1948. H. w. SHELE JRICK CHAIR IRON FOR TILTABLE SEATS AND BACKS 2 Sheeo-Sheet 1 Filed May 25, 1945- Dec. 21, 1948. H. w. SHELDRICK 2,455,797

CHAIR IRON FOR TILTABLE SEATS AND BACKS Q Filed may 25, 1945 2 Sheets-Sheet 2 jwerze'ar flaw 5219126825723)? rearward tipping movement of the back.

Patented Dec. 21, 1948 CHAIR IRON FOR TILTABLE SEATS AND BACKS 'Henry W. Sheldrick, Gardner, Mass, assignor to Collier-Keyworth Company, Gardner, 'Mass., .a

corporation of Massachusetts Application May 25, 1945, Serial No. 595,684

2 Claims. 1

This invention relates to chairs or thetype em-v bodying a pivotally mounted seat and back such, for example, as ofiice chairs and the like.

The principal objects of the invention are to providean improved chair iron in which the seat and back are supported for simultaneous tipping movement controlled by rearward pressure exerted on the back by the occupant, rather than by the weight or pressure exerted bythe occupant on the seat, and to provide a chair iron which is of simple construction, having a minimum number of parts and which may be economically manufactured and readily assembled with a seat; back and pedestal.

Further objects relate to various features and construction and will be apparent from a consideration ofthe following description and the accompanying drawings, wherein- Fig. 1 is a side elevation of an office chair mbodying the present invention.

Fig-2 is a top plan view of the chair iron;

Fig. 3 is a section on the line 33 of Fig. 2; and

Fig. 4 is a diagrammatic view showing the relative positions of the seat, back and associated members of the chair iron at different angular positions.

In accordance with the present invention I provide a chair comprising a base or the like supporting member which may be of conventional design and construction, separate seat and back members which may also be of conventional design and construction, and a chair iron carried by the base member and supporting both the seat and back for simultaneous tipping movement, the chair iron comprising a four-bar linkage system so designed that the occupant of the chair may control the tipping movement of the seat by exerting pressure on the back. To this end resilient means, such as a compression spring or the like, are provided to act on the linkage system so as to oppose tipping movement of the seat with a substantially greater component of force than the component operative to oppose In addition, I provide means whereby the angular position of the back may be adjusted relative to the seat, thereby securing the desired angular relationship between the seat and back which is more conducive to the comfort of the occupant.

' In the embodiment herein shown for the purpose of illustration a conventional pedestal or base is supported on casters 2 and a chair iron 3,- carried by the base, supports separate seat and back members 4 and 5. The seat and back,

2 members may be of conventionaldesign and con struction and, if desired, the seat may be provided with arm rests 6, it being understood that the back rest 5 is supported independently of the seat 4 and arm rests 6, as hereinafter described.

Thechair iron 3 comprises a fixed member consisting of a pair of spaced parallel angle irons l and H rigidly connected at their central portions by a U-shaped member |2 which is rigidly secured to the upper part of a post |4 threaded into and supported by a cap l disposed on the top of the pedestal. The fixed member is normally supported in a slightly inclined position, as shown in Figs. 1 and 3, by the U-shaped member l2 and a plate l6 (Fig. 3) is formed with an opening to receive the reduced end of the post M which is peened over the margin of the opening, as indicated at |8,to provide a strong and rigid connection between the chair iron and pivot.

Spaced parallel angle irons and 2|, collectively constituting a seat-supporting member, are pivotally connected adjacent to their front ends to the corresponding ends of the angle irons l0 and II, respectively, by rivets 22 or the like pivots, and adjacent to their rear ends, the seatsupporting members 20 and 2| are pivotally connected to depending links 24 and 25 by rivets 26. The upper ends of the links 24 and 25 project beyond th pivots 2B and are bent inwardly to provide stops 28 and 29 engageable with the upper wings of the fixed members l0 and H to limit downward tipping movement of the seat-supporting members 20, 2 I, relative to the fixed members In and II.

.The fixed members In and H are interconnected with links 24 and 25, respectively, through a back-supporting member. 30 which consists of a hollow, generally wedgeeshaped steel member having side walls 3| and 32 and a depressed bottomwall 3-3. The side walls 3| and 32 snugly fit between the vertical wings of the fixed members Ill and H, and are pivotally connected thereto at the upper corners by rivets 35. The lower ends of links 24 and 25 are inwardly ofiset, as shown in Fig. 2, and are pivotally connected to the central portion of side walls 3| and 32, respectively, by rivets 35. The tap-ering rear end portion of the member 39 (the parts of the side and bottom walls to the left of pivot 36 in Fig. 1) provides an extension 38 to which the back 5 is connected in the manner hereinafter described.

A transversely extending strap 40 having a depressed central portion M is, riveted or otherwhich maintains the spring properly centered to':

prevent rubbing the bolt 42. The lowerendof the spring acts against a washersuppol'tedbytlie hub of an adjusting hand wheel 46 threaded'on' By turning. theahandfwheeli 45 in one direction or the otherrit'sipositicrrmayf,

the end of bolt 42.

be adjusted axially of the bolt so as to vary -the force exerted by spring 45 onrthefixedimembers I iii, in and the back-supporting member twin of the latter about pivot 35.

With this; construction and; arrangement downwardly-tiltingZ-movement-of the'seat 4-ofthe chair is; yieldingly opposed by; the spring 45, acting through ;-member -.and:;links 24 and-25; and rearward vtiltingmovement. of the back 5: is yieldingly-opppsed spring; acting-through extension 38-; Thewdesignof-parts is such that the force necessary-toefiect'downward' tilting movement of the sea-tis many,times-greaterthan that necessary to .efiect rearward, tilting :movement of the back;

The rear end of extension.38:is.;pivotally con sides 3i and=32 ,offthetmember 313::v Oneend-iof' the shaft 58' extends outwardlyiandscarries -a hand wheel Knot shownl by'inieansiof which the shaft; and: hence the stem may .be-;rotated in one direction or thexotherto. vary the efi'e'ctive length of the link 53, which controls the normal angle of inclination of .the back 5:.

Inthe construction. and. arrangement... above described the fixed members I0 and II, the seatsupporting members 20 and 2!, the links 24' and 1 25, and the back-supportingmember lid/constitutea four-bar linkage system, illustrated in Fig. 4, wherein the fixed members, seat-support ing members, links, and back supporting memyieldingly opposing downward pivotal mbterii enm her are represented by the lines a-'b, a-c, c--d, v

and bd, respectively, andlthe pivotal connections 22, 35;. 26 and 36are respectivelyrepresented by the points a, b, c and d; th'e-lin'ed'g represents the extension 38; the line e-g represents the back 5-of the chair; and angle 'fge i's constructed equal to angle cac', and'li'ne f'g "is parallel to the upper extension ofline bde' to correspond to theposition of the seat'5'and asso-- ciated 1 parts when tiltedfrom normal position;

indicated by the full lines.

When the back member of the chair; represented by line e-g, is tilted "toward the rear; at

the same time the seat is loweredfrom the position ac to ac'. The backhas an angular.

, against i said: fixedrmember: and: saidsbac 4 travel equal to egf', and due to the fact that angle egf is greater than angle egf by an amount equal to angle fgf, the occupant of the chair can force the seat down at will by exerting pressure against the back. This is an essential characteristic in order that the chair iron mechanism can beused -bmpeopleaof varying-sweightiwithout havingto ima e individual iarl justfhents for. each occupant of the chair. When rearward pressure is applied by the occupant to the back member a.-g d.b, which is pivoted to the fixed memberra batbj link dc is drawn downwardly,

causing seat 11-0 to be lowered to a more inclinedizpositibii itipivots on the fixed mem- Wat-"cw Since the moment arms of the fereeemtnebatka being the distance from the pointaonthe back where the force is applied to "the pivot point i) and being greater than the meilient=arm bd of the force on the seat, less pressure on the back is needed to compress spring; 45?; than a weight 3 on; the seat; andz hence unique-:1 arrangement a of: the 1 members: thus permits theLocCUpantwf theas'eat; irrespectiveil'oi his weight;.:-to ;control ithe: tiltinget'actlbrr merely by. applying pressure to: thee; back: of the; seat, rather: than: by: th'ei weight or: pressure. exerted by: the. occupant: on:theeseataasxin'.conventional constructions;

While:.-I;-.have shownnandtdescribedlione idesire able. embodiment-of thezinvention', it :.is.;t'o be understood: that this. disclosure: is: for the .pur; pose: of illustration and ithat various 'ch'anges. in shape-, proportion andi arrangement? ofparts, as well as the substitutes andmquival'ent:elements for thosev hereinshown 1 an'd'i described; may: be made .1 without: departing from; the spirit? and scopeaof thewihventionrasaset forth in themap pended claims:

I'claim: v

1. In a chairot th'e typeahaving separataseai and back: members,la 'chalr ir n.-.for supporting the seat? and. back rri'embersu for. simultaneous tipping movement, comprising a fixed member; a seate'supportingl member. pivot-ally: connected :Ito said: fixed membersadjaeentrto oneaend.-, a= back supporting: memberx pivotallyvconnectediz tarsal-id fixed member adjacent to its opposite end, aalink pivotallyconnected:to:said:seatesupporting members and. to; said backesupportingx member; the upper end 101 said linkzhavirigfa stop. engageable withsaid fixed tgmember, fort-limiting the: downeward tipping; movementvsof Saldi seat-supporting: member relativecto.saidafixedzamember, and :reia silient r'rhe'ans constructed:andzzaicranged:toereaet ejsup-r porting memberc so asctoropposexdownwardz;tips, ping: movement: of: the: seat"; member-r with a greater, force than:thevforcer oppgsing, {rearward tippingi'movement :of :s'aid .iback member;

2 In; 2.; chain otztheztypeehavin-g separate: seat and: back? -.ri1e1nbers,- a: .chairiiiion for supporting the seat hrrdebackqmember's forrsi-multaneous tip! pingrmovement; comprisingz; an fixed .membert; a seatsupporting member piyotallyrconn'ectedrto said fixed: member an; accent (tor: its -'=fi"ont :end; .a' backf-"supportingzmemberrpivotallyiconnected c: said: fixed: .member at a point-spacedsinwardlyofi thesr'ear e'ndfor 'saidilixednnemberzs'osas todefine a rearward projection; said-:1 baeksu'ppoiitin'gz member having- 'a -i'a1 W-ard- "e to said biack r tosaid seat-supporting mem'berand o 'saidrbacke supporting member: at a: point f1 adjacent fto the inner ena of 5: said' extensio the: upper end of Said lihk having? a stoii engageab1e with said fixed member for limiting the downward tipping movement of said seat-supporting member relative to said fixed member, and resilient means constructed and arranged to react against said projection and extension so as to oppose down? ward tipping movement of said seat member with a greater force than the force opposed rearward tipping movement of said back member.

HENRY W. SHELDRICK.

REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Chichester Aug. 1, 1876 Chioh-ester June 16, 1903 Dexter May 3, 1910 Sengpiel May 16, 1933 Foote Jan. 1, 1935 Bolens Aug. 13, 1940 Herold June 8, 1943 Sheldrick Feb. 8, 1944 Herold 1- Apr. 24, 1945 

